206435006581 has 2 divisors, whose sum is σ = 206435006582. Its totient is φ = 206435006580.

The previous prime is 206435006573. The next prime is 206435006647. The reversal of 206435006581 is 185600534602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 176173272900 + 30261733681 = 419730^2 + 173959^2 .

It is a cyclic number.

It is not a de Polignac number, because 206435006581 - 2³ = 206435006573 is a prime.

It is a super-2 number, since 2×206435006581² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (206435006501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103217503290 + 103217503291.

It is an arithmetic number, because the mean of its divisors is an integer number (103217503291).

Almost surely, 2^206435006581 is an apocalyptic number.

It is an amenable number.

206435006581 is a deficient number, since it is larger than the sum of its proper divisors (1).

206435006581 is an equidigital number, since it uses as much as digits as its factorization.

206435006581 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 172800, while the sum is 40.

The spelling of 206435006581 in words is "two hundred six billion, four hundred thirty-five million, six thousand, five hundred eighty-one".